It is conventional in the field of restorative dentistry to cover the metal framework of a dental prosthesis or restorative restoration such as a crown or bridge with a polymeric veneering material such as acrylic or a porcelain ceramic to simulate the aesthetics of natural teeth. The veneering material forms the superstructure for the prosthesis or dental restoration after it is fused to the underlying metal framework at relatively high temperature. A superstructure of a porcelain ceramic composition may be formed of, for example, natural feldspar, quartz and kaolin and may possibly also include borosilicate glasses, flux and a coloring agent.
To enhance the bond strength between the metal framework and a porcelain superstructure it is conventional practice to apply a bonder to the surface of the metal framework upon which a porcelain ceramic material is coated before firing the porcelain ceramic at relatively high temperature in a dental furnace. A typical bonder contains a composition of finely divided particles of noble metals essentially or entirely of gold. An alternative bonding material which enhances the bond between a porcelain ceramic and a metal framework particularly of a noble metal or alloy composition is described in U.S. Pat. No. 4,434,211 the disclosure of which is herein incorporated by reference. In accordance with the aforementioned patent the bonder includes particles composed of a halide of a noble metal in a range of between 1 to 100% by weight of the bonder composition. Although a bonder having a halide of a noble metal results in a clinically unbreakable bond the success in forming a bond of satisfactory bond strength is nevertheless dependent upon firing the porcelain ceramic under controlled conditions in a relatively narrow temperature range.